Practical Schemes on Lightning Energy Suppression in Arresters for Transformers on 10 kV Overhead Distribution Lines

This paper presented an assessment of lightning energy absorption by dedicated surge arresters (SADT), which are provided to protect the distribution transformers on 10kV overhead distribution lines (OHLs). A hybrid Partial Element Equivalent Circuit-Multi-conductor Transmission Line (PEEC-MTL) code was applied to evaluate lightning surges on SADT. This method has the capability of modeling both short and long wires in OHL systems and is verified numerically and experimentally. A Monte Carlo procedure was adopted to assess the fault rate (FR) of SADT. It is found that the direct lightning strokes to the phase wire are the primary threat to the SADT, compared with the strokes to the poles as well as indirect strokes to the ground or structure nearby. Several protection schemes are identified, and their performance is evaluated from the aspects of lightning protection and economic cost. The full shielding wire (SW) scheme performs the best, but with the most expensive protection cost. The lightning energy absorption by SADT can be suppressed significantly by installing extra SAs on the adjacent poles. The scheme of four extra SAs together with a partial SW can achieve a balanced performance of protection effect and economic cost for the OHL.